The standardization of optical transport networks (OTN) is currently ensuing. A critical feature of the architecture of transport networks is the independence of the individual transmission layers, which control the transmission between different network elements, amplifiers or multiplexers for example. These layers can be planned, administered and monitored independently of each other.
It is an object of the present invention to provide a method for monitoring the signal quality given an optical transport network conceived in such a manner.
In general terms the present invention is a method for monitoring the signal quality of a transmission signal in optical data networks. The signal quality is measured within the same time intervals at the beginning and end of a transmission path. the time intervals are set by a measuring means at the transmission side. Corresponding time marks, as well as measuring results are transmitted to a measuring means at the reception side at the end of the transmission path via an additional channel. The measuring means at the reception side transmits these measured values and its own measured values to a central location or evaluates the measured values itself and transmits a measuring result.
Advantageous developments of the present invention are as follows.
Separate measurements are carried out for each WDM transmission channel given the transmission of a wavelength multiplex signal.
Each WDM transmission channel has a service channel allocated thereto.
The same timing mark is used by the measuring means at the transmission side for a plurality of transmission paths or path sections. The measuring results of a plurality of transmission paths or path sections are transmitted via the service channel. The measured values are transmitted to the central location by the measuring arrangement of the last path section.
The same timing mark is used by the measuring arrangement at the transmission side and the measuring arrangement at the reception side for measurements in a plurality of WDM transmission channels.
The measured values are transmitted as time multiplex signals in a service channel.
Respectively one service channel is allocated to a WDM transmission channel by overlay techniques.
Measured values that belong together, are evaluated in the measuring arrangement at the reception side and the modification of the signal quality that is caused by the transmission path is transmitted to the central location as a measuring result.
The present invention is also a method for monitoring the signal quality of a signal in optical data networks. The signal quality is measured within the same time intervals at the beginning and the end of a transmission path. The time intervals are controlled by a central location. The measured values are transmitted by measuring means to the central location, which evaluates the measured values.
The advantage of the invention is the exact coincidence of the measuring intervals appertaining to the same data sequences at the beginning and the end of a transmission path. Monitoring results of one or also a plurality of transmission paths can be transmitted via an allocated service channel.
A central location evaluates the measuring results and can initiate appropriate steps given decreasing signal quality.